1. Field of the Invention
This invention pertains to medical equipment, and more particularly to apparatus used in orthopedic surgery.
2. Description of the Prior Art
External fixators for stabilizing fractured or osteotomized bones are well known. Such fixators immobilize damaged bones and thus aid natural healing processes to repair the bones.
In the use of external fixators, threaded metal pins are screwed into appropriately tapped holes located on opposite sides of the bone fracture. The pins protrude through the muscle, subcutaneous tissue, and skin. A frame is assembled to the exposed ends of the pins to join them together. The fixator frame rigidly retains the pins and thus the associated bones in place while healing occurs. Typical external fixators may be seen in U.S. Pat. Nos. 4,127,119 and 4,620,533.
Because biological tissue does not adhere to the metal fixator pins, a chronic break remains in the skin around the pins. As a result, a rather common complication involving external fixators is infection that occurs around the pins. Investigations have shown that infections occur in about 10% of the pins used in external fixators. The infections range from superficial skin infection to deep bone infection, i.e., osteomyelitis.
The primary treatment for external fixator pin infections is antibiotics. However, antibiotics are often ineffective. In those situations, it is necessary to remove the pins and place them at new sites. In severe cases, use of the external fixator must be terminated.
U.S. Pat. No. 4,856,504 describes antimicrobial wound dressing and skin fixator for orthopedic pins that includes an annular patch containing an antimicrobial agent. The patch is placed over an orthopedic pin and against the skin. The patch is held in place by a pad of pressure-sensitive adhesive. A flange overlies the patch and pad, and the flange is secured to the fixator pin. Although the antimicrobial patch of the 4,856,504 patent is helpful for preventing infection around a pin, it does not contribute to the natural ingrowth of tissue around the pin so as to bring into play the natural defenses of the body to bacterial infection.
Thus, a need exists for improvements in the prevention of infections associated with external fixators.